1. Field of the Invention
This invention relates to an improved process for the manufacture of an expansion joint material and to the resultant expansion joint material.
2. Description of the Prior Art
Expansion joint materials are used in connection with various structures, particularly concrete types such as bridges, roadways, sidewalks, airport runways and the like. Since these latter structures tend to expand and contract with temperature changes, the expansion joints commonly are interposed at certain fixed intervals in the structures. Such expansion joints necessarily must be resilient and concomitantly must be enduring and not readily affected by moisture or be subject to deterioration when exposed to the elements. For practical purposes, the joint also should be capable of being efficiently handled and put in place without an undue amount of skilled labor. The joint further should be producible at a reasonable cost.
Heretofore, highly satisfactory expansion joints having the above characteristics have been formed from boards composed of fibers securely bonded together and uniformly saturated with asphalt to insure longevity. These fiber expansion joints are typically produced by cutting an asphalt saturated fiberboard into strips of a desired width and length. The fiberboards are first formed and then saturated in a subsequent operation by dipping into a solution of asphalt and a solvent, whereby a satisfactory penetration of the fiberboard by the asphalt is accomplished.
Unfortunately, there are a number of distinct disadvantages associated with the saturating and follow-up board drying procedures. These steps are time consuming, laborious, expensive, and potentially dangerous. The special trouble with the procedures stems from use of the solvent which, although it particularly furthers the asphalt's penetration into the fiberboard, is difficult to handle and has the potential to be hazardous. Without the proper precautions, the hazards from use of a solvent include the risk of fire, explosion, and pollution of the workplace environment and the atmosphere, together with the possibility of attendant health problems for the workers and others who come in contact with the solvent or its vapors. Furthermore, the loss of expensive solvent during the operation can add significantly to the cost of production. Measures to curb such solvent loss also can increase the operation's expense.
There accordingly is a need for an efficient and relatively inexpensive method which requires the use of little or no solvent for making expansion joints having all the characteristics desired in such materials.